# -*- coding: UTF-8 -*-
import os
import random
import time
from multiprocessing import Process, Queue, Pool


def long_time_task(name):
    print('Run task %s (%s)...\n' % (name, os.getpid()))
    start = time.time()
    time.sleep(random.random() * 3)
    end = time.time()
    print('Task %s runs %0.2f seconds.' % (name, (end - start)))


def pool_run():
    print('Parent process %s.' % os.getpid())
    p = Pool(4)
    for i in range(5):
        p.apply_async(long_time_task, args=(i,))
    print('Waiting for all subprocesses done...')
    p.close()
    p.join()
    print('All subprocesses done.')


def run_communication():
    def write(q):
        print('Process to write: %s' % os.getpid())
        for value in ['A', 'B', 'C']:
            print('Put %s to queue...' % value)
            q.put(value)
            time.sleep(random.random())

    def read(q):
        print('Process to read: %s' % os.getpid())
        while True:
            value = q.get(True)
            print('Get %s from queue.' % value)

    q = Queue()
    pw = Process(target=write, args=(q,))
    pr = Process(target=read, args=(q,))
    pw.start()
    pr.start()
    pw.join()
    pr.terminate()  # 因为read方法死循环、需要主动结束


if __name__ == '__main__':
    # pool_run()
    run_communication()
